In a projector which is an image projection device that projects and displays an image on a screen or the like, a failure of equipment and degradation of optical components are more likely to occur in accordance with the usage time and usage environment. For example, in order to prevent dust intrusion into the projector, the projector is provided with a filter at an air inlet. However, as the usage time of the projector increases, dust adhering to the filter increases. Accordingly, the pressure loss increases, and taking-in of cooling air into the projector is inhibited. In the case where such a state progresses further, the inside of the projector can no longer be cooled sufficiently, and damages to various devices arranged within the projector, in particular, optical devices, are likely to occur to shorten the life. The filter life is generally shorter than the life of the projector main body, and periodic filter replacement is necessary.
For such a situation, an external filter that covers the projector main body, for example, has been proposed (for example, Patent Literature 1 and Patent Literature 2). In addition, in order not to reduce cooling performance of the projector, a technology for providing a cooling device having a cooling fan and a Peltier element within the projector, and achieving both noise reduction and effective cooling has been proposed (for example, Patent Literature 3).